Cryptozoic Entertainment has announced the February 2013 release of World of Warcraft TCG Set 20: Timewalkers, Betrayal of the Guardian, the second set in the Timewalkers block that features legendary characters from the Warcraft and Warcraft 2 eras. Players will be able to add even more Humans, Night Elves, Orcs, and Tauren to their racial decks while taking advantage of new abilities and allies. A new keyword, "Rift" is introduced in the set, and it will allow those who maintain the integrity of the timeways access to powerful abilities, allies, and equipment much earlier in the game than ever before.

The card set introduced by Timewalkers, Betrayal of the Guardian features a total of 232 cards. Each Timewalkers, Betrayal of the Guardian Booster Pack (MSRP $3.99) contains 16 cards, 15 game cards (10 common, 4 Uncommon, 1 Rare, plus 1 crafting/token card). Three "loot" cards will be randomly inserted throughout the run. The "loot" cards for this release, which can be redeemed for perks in the online WoW game, include “Floating Spellbook” (common), “Dark Portal Hearthstone” (uncommon), and “Ghostly Charger” (rare).

Cryptozoic is also planning to release the World of Warcraft TCG Set 20: Timewalkers, Betrayal of the Guardians Epic Collection (MSRP $39.95), which contains a reusable storage box with dividers, a Betrayal of the Guardian playmat, a Betrayal of the Guardian deck box, six Betrayal of the Guardian Booster Packs, a Betrayal of the Guardian pocket guide, five random foil heroes from the Timewalkers block, and one common "loot"” card ('Floating Spellbook").